Manufacture of gelatine blasting explosives



Patented Aug. 8, 1950 ENTT cmce MANUFACTURE or GEIJATINE BLASTIN'G r EXPLOSIEYES Reginald John William Reynoldaizfilackley, Mamchestcr, England, and Stanley Fol-dham Salt coats, Scotland, assignors; to lmperial Chemical Industries" Limited, a corporation. of Great Britain N0 Drawingpnpplication May rigisrclserial No;

, 670,520 InGreat Britain: JuneA', 1945 The present invention relatesto the manufac turef'of' improved 'orymodified, gelatine] blasting explosives.

By the term gelatine blasting explosives We mean. blasting expl'osive oi coherent consistency containing a sufficient proportion ofuaijelliyfcomprising nitrocellulose in solution in one'o'r more liquid explosive'nitric esters-to render the explosive capable of being cartridged by extrusion. The most-powerful of the gelatine'blasting explosive compositions, known as Blasting Gelatine, consists aoif'practi'cally undiluted"; liquid nitric ester-nitrocellulose jelly, and. there is also avail able a series of less powerful explosives which compriseivegetable tissue. materials of more, or less porous structure and ofv oxidisable character and. oxidising salts, for instance wood-meal and inorganicnitrates, distributedjthrlough, a liquid nitric.ester nitrocellulose jelly. The presentinvention is especially applicable to high power gelatine blasting explosives which contain only relatively small amounts of vegetable tissue material and a relatively high proportion of liquid explosive nitric ester-nitrocellulose jelly.

As is well known there is a tendency for storage to reduce the sensitiveness of gelatine blasting explosives to initiation as indicated, for instance by a Gap Test in which two cartridges are aligned co-axially at pre-arranged distances apart and one of them is primed with a detonator at the end remote from the other cartridge. This tendency towards loss in sensitiveness on storage is at least partly occasioned by the gradual loss of the small entrapped air bubbles introduced into the composition in the course of the mixing operations in its manufacture, and occurs more rapidly on hot storage. The loss in sensitiveness is usually especially marked in the case of high power gelatine blasting explosives, which ordinarily contain a high proportion of liquid explosive nitric ester-nitrocellulose jelly and at most only small proportions of porous vegetable tissue materials, which themselves occlude air and thus provide more or less permanent air inclusions in the compositions.

It is an object of the present invention to provide gelatine blasting explosives, and more particularly to those of high power as aforesaid, containing for instance not less than 60 per cent of liquid nitric esters gelatinised with nitrocellur 4 Claims: (circa-1a) lose, in which the tendency to lose sensi-tiveness to initiationion storage, and especiallyon hot stora eis reduced. a

It has-already been proposed to form angel from a solution of nitrocellulosedon example'innitro-benzene, by a process which comprises treating the said solution'Wvith a cross-linking agent-comprising an organic diisocyanate; dimethylol urea-or a dia'lkyl ether thereof; ametlr-i ylol-melamine or-an-ether thereof; an N-meth ylolor N alkoxymethyl polyamide,' or an N;-N -bis--( alkoxymethyl) derivative of a diamitie. era dicarboxylic acid.-

We have now-found that the presence-rof-avery small" amount of a-- nitrocellulose crossslinking. agent; comprising dimethylolwureaior a dialkyletherlthereof; a .methylol-melamine or an ether thereof; an organic'diisocyanate; an-N-methylole. or: N-alkoxymethyl-polyamide; an N :sN dii-metha ylol derivative of a diamide of a dicarboxylic acid; or an N:N bis (alkoxymethyl) derivative of a diamide of a dicarboxylic acid, amongst the ingredients of the gelatine blasting explosive during their incorporation, results in a marked diminution in the loss of sensitiveness on storage,

and especially on hot storage, of the resulting explosives.

Accordin to the present invention, therefore, a gelatine blasting explosive has included therein a nitrocellulose cross-linking agent.

Examples of suitable nitrocellulose cross-linking agents include the hexa-methyl ether of hexa-methylol-melamine; the dibutyl ether of dimethylol urea; hexa-methylene diisocyanate, and di-methylol adipamide.

The amount of the nitrocellulose cross-linking agent employed may conveniently be from about 0.05 to 0.5 per cent. Since the quantity of the cross-linking agent is small and the temperature at which explosive compositions are mixed is never very high, the presence of the cross-linking agent does not render the consistency of the explosive appreciably stilfer during the mixing operation and the cartridging or other operations involved in the manufacture of explosives. The manner in which the cross-linking agent is brought into contact with the other ingredients of the explosive is largely a matter of convenience. For instance, it may be mixed with the liquid explosive nitric ester before the nitrocellu- Example 1 Per cent. Nitrated 80:20 mixture of glycerine and ethylene glycol 91.1 Nitrocellulose of nitrogen content 12.2 per cent made from linters by the mechanical process 8.2 Dibutyl ether of dimethylol urea 0.1 Chalk 0.6

The ingredients were first mixed together for a few minutes by hand and the resulting mass was transferred to a McRoberts mixer in which it was mixed at a temperature of about 30 for about 56 minutes. The resulting explosive was cartridged by extrusion. After storage for three months at C. the explosive still propagated 1 detonation over a gap of '7 inches is a Gap Test as aforesaid. An explosive containing 91.2 per cent of the nitrated 80:20 mixture of glycerine and ethylene glycol, 0.6 per cent chalk with 8.2 per cent of the same nitrocellulose similarly mixed, cartridged and stored for the same time at the same temperature propagated only over a 0 gap of 1 inch in the Gap Test.

Example 2 Per cent. Nitroglycerine 91.2 Nitrocellulose as used in Example 1 8.2

Hexa-methyl ether of hexamethylol melamine 0.1 Beta-napthyl methyl ether 0.5

The ingredients were mixed and cartridged as in Example 1. After storage for one week at 60 C. this explosive propagated over a gap of 1 inch in the Gap Test as aforesaid, whereas an explosive made with the same variety of nitrocellulose but without the hexa-methyl ether of hexamethylol melamine, in which the percentage of nitroglyccrime was correspondingly increased, failed to propagate detonation to a second cartridge in contact with the first cartridge in the Gap Test, although the first cartridge was satisfactorily initiated by the detonator.

We claim:

1. A gelatine blasting explosive composition formed from a mixture comprisin at least per cent of a liquid explosive nitric ester, nitrocellulose containing unreacted. hydroxyl groups, and between 0.05 to 0.5per cent of a, nitrogen containing nitrocellulose cross-linking agent selected from the group consisting of dimethylol urea, a dialkyl ether of dimethylol urea, methylol,-melamine, a hexaalkyl ether of methylol melamine, an NN bis (alkoxymethyl) diamide of a dicarboxylic acid, and an NN dimethylol diamide of a dicarboxylic acid.

2. A gelatine'blasting explosive as claimed in claim 1 wherein the nitrogen containing nitrocellulose cross-linking agent is dibutyl ether of dimethylol urea.

3. A gelatine blasting explosive as claimed in claim 1 wherein the nitrogen containing nitrocellulose cross-linkin agent is dimethyl ether of dimethylol urea. v

4.1 A gelatine blastingfexplosive as claimed in claim 1 wherein the nitrogen containing nitrocellulose cross-linking agent is the hexamethyl ether of hexamethylol melamine.

REGINALD JOHN WILLIAM REYNOLDS; STANLEY FORDI-IAM.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

1. A GELATINE BLASTING EXPLOSIVE COMPOSITION FORMED FROM A MIXTURE COMPRISING AT LEAST 60 PER CENT OF A LIQUID EXPLOSIVE NITRIC ESTER, NITROCELLULOSE CONTAINING UNREACTED HYDROXYL GROUPS, AND BETWEEN 0.05 TO 0.5 PER CENT OF A NITROGEN CONTAINING NITROCELLULOSE CROSS-LINKING AGENT SELECTED FROM THE GROUP CONSISTING OF DIMETHYLOL UREA, A DIALKYL ETHER OF DIMETHYLOL UREA, METHYLOL-MELAMINE, A HEXAALKYL EITHER OF METHYLOL MELAMINE, AN NN'' BIS (ALKOXYMETHYL) DIAMIDE OF A DICARBOXYLIC ACID, AND AN NN'' DIMETHYLOL DIAMIDE OF A DICARBOXYLIC ACID. 